Pg. 34 Use the following terms to construct a concept map of the six major crystal systems: Gypsum Topaz Pyrite Triclinic Cubic Hexagonal Tetragonal Crystal systems Wulfenite Pyromorphite Feldspar Orthorhombic monoclinic

PG. 17 Identifying Minerals

Mineral Identification Geologists rely on simple tests to identify minerals Based on chemical and physical properties Usually a combination of tests

Color Sometimes trace elements cause certain characteristic colors Least reliable clue for identification

Luster The way a mineral reflects light Described as being either metallic or nonmetallic Differences in luster are caused by difference in chemical compositions

Texture How the mineral feels to touch Words used to describe: smooth, rough, ragged, greasy, soapy

Streak The color of a mineral when it is broken up and powdered. Rubbed across an unglazed porcelain plate. A minerals streak doesn’t always match its color Streak color is always the same

Hardness A measure of how easily a mineral can be scratched Most useful tests Use Mohs hardness scale Fingernail= 2.5 Penny= Masonry nail- 5.5 Harder will scratch softer

Cleavage and Fracture Minerals break along planes where atomic bonding is weak Minerals that break easily along a plane are said to have cleavage Minerals that break with rough edges are said to fracture

Density and Specific Gravity Specific gravity is the ratio of the weight of a substance to the weight of an equal volume of water. Density reflects atomic mass and structure of a mineral

Mineral Uses Ore- a mineral that is useful if it can be mined for a profit Ex. Aluminum (comes from bauxite) Iron (comes from hematite) Use mines to obtain ores Gems are valuable minerals